1. Field of the Invention
The present invention relates to a seat for a vehicle and a seat for watercraft, particularly to a seat for a vehicle and a seat for watercraft wherein a polyurethane and a thermoplastic elastomer are used for cushion bodies covered with a seat skin.
2. Description of Background Art
As an example of a seat for a vehicle, there has been proposed a seat for a vehicle wherein a predetermined space defined by a first cushion body, such as a polyurethane foam, provided adjacent to and on the inside of a seat skin and an armor member composed of a bottom plate is charged with a lump-form thermoplastic elastomer-made second cushion body so as to leave a gap at the outer periphery of a side surface portion, thereby contriving enhancement of the ride comfort of the seat (refer to, for example, Japanese Patent Laid-Open No. Hei 10-295498).
However, in the seat for a vehicle as described in Japanese Patent Laid-Open No. Hei 10-295498, it is only shown that members differing in properties are used for the cushion bodies used in the inside of the seat, and such a mere combination may rather worsen the ride comfort. In addition, the predetermined space defined by the first cushion body and the armor member composed of the bottom plate is charged with the second cushion body so as to leave a gap; therefore, for example, a corner portion between the upper surface and a side surface of the thermoplastic elastomer-made second cushion body may be sensed as a hard edge upon seating, or a hardness of some region of the seat different from the hardness of the surrounding regions may be sensed as a foreign matter during running, whereby the ride comfort may be worsened.
The reason for the worsening of the ride comfort is considered as follows. At the time of absorbing vibrations or shocks transmitted from a road surface or the like or at the time of dispersing the driver's weight, the load absorption characteristic and/or propagation characteristic may become discontinuous at the boundary portion. between the polyurethane-made first cushion body and the thermoplastic elastomer-made second cushion body, and a portion where the vibration absorption performance or the load dispersion performance is spoiled may be locally generated.